With the progress of fabricating technique, various display applications are developed out. To meet the requirements of lighter, thinner, shorter, smaller, and more portable, the development of display applications of the next generation is focused on the flexibility and portability. Currently, flexible displays and electronic paper displays attract considerable attention and are also well researched and developed.
Nowadays, thin film transistors are widely used in various display devices. Thus, the structure design and the materials of thin film transistors significantly affect the performance of display devices.
Generally, a thin film transistor at least includes a gate electrode, a source electrode, a drain electrode and a channel layer. The conductivity of the channel layer can be controlled by adjusting the potential of the gate electrode such that the source electrode and the drain electrode are electrically conducted (on-state) or isolated (off-state). In known thin film transistors, channel layer usually includes amorphous silicon (a-Si) or poly-silicon (p-Si).
However, a high process temperature is required for thin film transistors having channel layer of either a-Si or p-Si. Furthermore, flexible display devices usually include a flexible substrate such as a plastic substrate. As commonly known, plastic substrate has a low softening temperature. Thus, when thin film transistors with channel layer of either a-Si or p-Si are applied into flexible display devices, the flexible substrate transforms or deteriorates in the fabricating process of thin film transistors. Therefore, the known thin film transistors are not suitable for being applied into flexible display devices.